Radiator core



May 4, 1937a F. yM. Pljrz .2,079,032

RADIATOR CORE Filed Feb. 2,5, 1955 '7 Sheets-Sheet 1 Y fn Uenon' Fed/H pz.

May 4, 1.937. i F `M QPlTz i v 2,079,032

RADIATOR CORE v Filed Feb. 25, 1935 '7 Sheets-Sheet 2 v Emmi, Up.

May 4, 1937. E M, OPITZ 2,079,032

RADIATOR CORE Filred Feb. 25, 1935 '7 Sheets-Sheet 3 y l f'ffeno Fed/U Upz May -4, 1937. l F. oPlTZ I 2,079,032

RADIATOR CORE Filed Feb. 25, 1935 '7 Sheets-hee? 4 May 4, 1937. F. M. oPlTz 2,079,032

RADIATOR CORE Filed Feb. 25, 1955 7 Sheets-Sheet 5 May 4, 1937.

F. M. oPlTz RADAToR CORE Filed Feb. 25, 1935 7 Sheets-Sheet 6 May 4, 1937. l F. M. oPlTz 2,079,032

RADIATOR CORE Filed Feb. 25, 1935 '7 Sheets-Sheet 7 nY Inf/@afan Wed/M. 0,0242

Patented May 4, 1937 ATENT oFFicE RADIATOR CORE Fred M. Opitz, Milwaukea Wis., assigner to Hexceladiator Company, Milwaukee, Wis., a corporation of Wisconsin Application February 25, 1935, Serial No. 7,957

15 Claims.

The present invention relates to radiators, and is particularly concerned with the provision of a new and improved radiator core of the fin and tube type.

A further object of the present invention is the provision of a radiator core of great strength and durability, andwhich possesses strong resistance to twisting and weaving stresses. In this connection, a :further object of the present l invention lies in the provision of a radiator core in which not only are the tubes freed completely from structural loads but, in addition, the tubes are so constructed that a free ow of water at all times occurs and the tubes are such as are not damaged when subjected to freezing pressures. More specifically, it is an object of the present invention to provide a radiator core of the 1in and tube type in which the ns, although individually connected with the tubes, are arranged to be interlocked together in self-sustaining relation so that, although they are secured to A.the tubes, the ns are not carried by the tubes.

A still further object of the present invention i is to provide a radiator having all of the advanthe saine time, does not possess the disadvan` tages of such radiators as regards their tendency `to become clogged and the tendency for soldered Y seams to open under freezing and mechanical stresses, especially those involved in the use of the radiator on moving vehicles and the like which are subjected to considerable vibration` More specically, it is an object of the present invention to provide a radiator oi the n and tube type in which the thermal eiliciency of the radiatoris not reduced by excessive amounts of solder or other relatively poor heat conducting metal.

An additional object of the present invention is the provision ofa radiator core of the fin and 1 tube type in which the marginal sections of the tubes are so constructed and arranged asto be highly resistant to damage by surface crushing and bendingand which, at the same time, affords 45 a general appearance somewhat like a radiator of the honeycomb or cellular type. Ordinary radiators of the iin and tubetype have fins which are easily bent upon being struck by even relatively light objects or light blows, and when bent such iins materially interfere with the flow of air through the radiator, thus appreciably reducing the eiiciency of the unit.

These and other objects and advantages of the present invention will be apparent from the, iollowing description o f the preferred Vstructural tages of radiators of the honeycomb and cellular embodiment, drawings.

In the drawings:

Figure l is a perspective View of one of the fins with sections bro-ken away at different portions; 5

` Figure 2 is a plan View of the n shown in Figure 1;

Figures 3, 4 and 5 are transverse sections taken, respectively, along the lines 3 3, 4 4, and 5 5 of Figure 2 and looking in the direction of 10 the arrows; Y

Figures y6 and l are longitudinal sections taken, respectively, along the lines 6 6 and 1 1 of Figure 2; Y

Figure 8 is a front view of a portion of a com- 15 pleted vradiator core with portions broken away along a central section;

Figure 9 is a sectional view of two iins, taken along the line 9 9 of Figure 2, illustrating how theiins are all formed alike and showing their uniformity of shape; i y

Figure 10 illustrates the relation between adillustrated in the accompanying Vjacent fins when alternate ones have been reversed end for end in the processof assembling the fins to form a radiator core, Figure 10 showl, ing the manner in which the crests of the corrugaticns carry interlocking means to receive complementary interlocking means carried by the ns intermediate the corrugated portions thereof;

Figure 11 is a perspective, including sections 30 taken generally along the line H I I of Figure 12 showing a modied form of strip;

Figure 12 is a plan view of the strip or fin shown in Figure 1l;

Figure 13 is a section taken along the line I3 I3 of Figure 12 looking in the direction of the arrows;

Figure 14 is a section taken along the line M ill of Figure 12; 4

Figures 15, 16, and k1'7 are longitudinal sections taken, respectively, along the lines I5 l5, |6 l6, and H ii of- Figure 12;

Figure 18 is a section corresponding to Figure 16 and showing two adjacent ns after one has been reversed end for end and ready to be me- 45 chanically interlocked together but before the water tubes have been inserted;

Figure 19 is aface view, with portions broken away along a central plane and illustrating a portion of the completed radiator core; 5g

Figure 20 is a section taken along the line 2li-2li of Figure 19 and illustrating in particular the manner in which the fins of the radiator core are interlocked together; and

Figures 21 and 22 are sections taken along the 55 lines 2|2| and 22-22, respectively, of Figure 20.

Referring now to the drawings, more particularly to Figures 1 to 10, it will be seen that radiator core constructed according to the principles of the present invention embodies a plurality of water tubes I and interlocked fins 2 of generally corrugated formation having crests 5 separated by intermediate portions 6. The marginal portions of the ns are also corrugated at opposite edges thereof, as at 8 and 9, preferably having a pitch a equal to the pitch of the central corrugations 5. As best shown in Figures l and 2, the central ccrrugations 5 are of truncated pyramidal formation, the marginal corrugations 8 and 9 being in the form of half truncated pyram mids. The sections 5, 8 and 9 are all in the form of protuberances extending from the same side of the general plane of the strip of metal forming the iin, the metal being thereby drawn or stretched in the formation of.the central and marginal corrugations or protuberances. This stretching of the metal is an important element of the present invention in that the active area of metal by which heat from the water tubes is radiated or dissipated is increased, according to the principles set forth in my prior Patent No. 1,706,584, issued March 26, 1929.

Each of the central corrugations or protuberances -5 include oppositely sloping walls 5a and 5b and end walls 5c, the end walls 5a sloping laterally in opposite directions from the crest of the protuberance 5, as best shown in Figure 3. The half corrugations 8 and 9 along the marginal .sections of the strip or n 2 have crests |2, flattened for purposes which will appear later, and bottom portions I3 opposite the intermediate portions 6 of the central series of corrugations or Lprotuberances A5. In order to avoid stressing the `metal of the .strip excessively the marginal corrugations 8 and 9 also have laterally inner walls l5 sloping toward the end walls 5c of the central corrugations. As best shown in Figures 1, 2, and 3, portions of the strip, indicated by the reference numeral I6, are extended from the sloping wall of the marginal corrugation to the adjacent sloping end wall of the central corrugation in order to relieve the strip of any excessive or localized stresses at this point in the formation of the central and marginal corrugations and their contiguously disposed sloping walls 5c and I5. The ridges I6 also provide for a somewhat greater air passageway through the core, as will be apparent from Figure 8. Between the flattened crests I2 of the marginal corrugations 8 and 9 are intermediate flattened or corrugated sections |8 which, as will be explained later, reenforce the face of the radiator core against crushing and deformation. Reenforcing the face and back of the core materially improves the construction because, if any of the air passageways are obstructed, the eiciency of the radiator is to that extent reduced, and corrugating the marginal sections in this manner, providing a number of angularly disposed sections, serves to secure materially greater strength of this portion of the radiator iin against being crumbled or crushed.

The core being of the n and tube type, the fins must have suitable openings to receive and contact with the water tubesv of the radiator core. According to the principles of the present invention, I provide the central portion of the iin with a series of tube receiving openings formed by first slitting and then piercing the fins in the manner set forth in my prior patent mentioned above. Preferably, each of the central protuberances contains three tube receiving openings, 2|, 22, and 23, the opening 2| being formed in the sloping wall 5a and the other two openings 22 and 23 bcing spaced apart laterally a distance slightly less than the length of the opening 2|, as shown in Figures 3 and 4, and formed partly in the other sloping wall 5b with the laterally outer end por tions of the openings 22 and 23 extending in the sloping end walls 5c. By virtue of this construction I have provided a row of tube receiving openings 2| in the center of the strip or fin and two rows of openings 22 and 23 disposed generally in the central portion of the strip but spaced apart as best shown in Figure 2, there being two openings on one side of the crest of each protuberance 5 and one opening on the other side. The distance longitudinally of the iin between the opening 2| and the adjacent two openings 22 and 23 of each protuberance 5 is substantially the same as the distance between the two openings 22 and 23 of one protuberance and the opening 2| of the next protuberance.

Each of the tube receiving openings 2|, 22, and 23 are formed, as mentioned above, by piercing, and this is for the purpose of .leaving inwardly extending flanges around the opening, as best shown in Figure 1 in which the flanges around the various openings are indicated, respectively, by the reference numerals 2|a, 22a, and 23a. By virtue of these flanges, a good contact between the iin and the tubes is had since the flanges are slightly resilient and will engage the tubes irrespective of any slight inaccuracies in the actual size of the tube receiving openings.

According to the principles of the present invention, means is provided whereby, when the several radiator ns are assembled in making the complete core, the ns form a self-sustaining assembly so that, even though they are not rigidly secured to the tubes but merely in contact therewith, the core unit as a whole is mechanical ly complete and rigid. By making the unit thus self-sustaining, the water carrying tubes are not called upon to support the fins and are therefore free to perform their own function of conducting the cooling medium. Moreover, the several fins or strips are mechanically interlocked together not only to secure and preserve their self-sustainling characteristic but, in addition, to facilitate the assembly of the core and the assembly of the water tubes and the several ns. However, even though the fins are corrugated and provided with means, which will be presently described, whereby the fins are mechanically interlocked, yet according to the principles of the present invention the several fins each have individual contact with the tubes and are therefore exceptionally efficacious in dissipating heat from the tubes.

Referring now for the moment to Figure 9, it will be seen that I have shown two ns or radiator strips as they come from the strip forming machine with the corrugations and tube receiving openings and flanges in nested relation, except that they are spaced apart in order to show the relations involved. In forming the radiator, the strips are severed at one end at the intermediate portion between the corrugations 5 and, at the other end, at the crest of the corrugation. Next, alternate strips are reversed or turned end to end, so as to bring the crests of one strip into registry with the intermediate or valley portions of the other strip, as best shown in Figure 10. As will at once beapparent, by virtue of this arrangement, the adjacent tubes are in contact at spaced points with the other portions of the strips separated and can then serve as air passageways -between the strips. Now in order to mechanically interlock the strips when alternate ones are reversed end for end, as just referred to, I provide an additional series of pierced openings, one to receive the other when the strips or fins are assembled in the relation shown in Figure 10. v i

Referring now to Figure 1 again, the interlocking means comprises flanged and pierced openings 3!) and 3| formed in the center of the strip andspaced longitudinally, the openings 30 3M and 3|a. As best indicated in Figures 9 and 10, the openings 3| in the crests of the corrugations or protuberances 5 are wider than the openings 30 formed in theintermediate sections of the n between the protuberances ofcorrugatween the flanges 3| a thereof, as best indicated in Figures 8 and 10, when the strips are reversed end to end in the relation shown in those figures. By virtue of this construction, then, the mere reversal and bringing together of alternate strips automatically secures all ofthe strips or fins in a mechanically interlocked and self-sustaining relation. The openings 3| receive the fianges 30a of the intermediate openings so that once the strips are brought to the position shown in Figure l0. the strips orns cannot get out of position either laterally or longitudinally with respect to each other. f

After the desired number of 'ns have been assembled in mechanically interlocked relation as set forth above, they are placed in a'jig, all

of the Water tube receiving openings being in alignment and held in alignment by virtue of the mechanical interconnection between the fins.` The fins or strips are then compressed Vto bring the radiator core to the desired dimension. and then the watertubes are inserted in the openings. Any suitable means may be used for placing the water tubes in position. For example, they may be inserted by hand since, by virtue of the pierced type ofv tube receiving openings and the flanges of the openings, it is a reiatively simple matter to push each tube in position. For this purpose, if desired. I may use a tool 35 best shown in Figure 8 having a reduced end 36 and a shoulder 3l. `The reduced end tson the inside of a tube and the shoulder engages the end thereof so that the tube may be quickly and easily sho-ved through the core openings into proper position.

The tub-es may be of any convenient construction, but preferably they are of the double seam type, formed of copper or any other suitable material, and they have their exterior surface tinned before they are inserted in the strips or fins. After al1 of the water tubes have been placed in position, end plates 40 (Figure 8) having suitable openings punched therein to receive the tube ends, are disposed over the ns. AThe end strips or plates Ml'are flat, and, like-the fins 2 described above, also have pierced openings 4| with flanges Illa.V After the end plates, `tubes and ns have been placed in position, theV jig is then removed and the core baked or heated to approximately 450 F. This is sulncient to melt*` the tin on the tubes, and subsequent cooling secures the end plates and the ns to the tubes themselves. After this is done, the frontfand rear faces of the core, that is, the marginal fin portions 8 and, 9, are dipped in a thin bath of solder for the purpose of securing the contacting portions of the marginal corrugations of the ns together.A It is to be noted that solder is Vnot applied to the tubes themselves but only Solder is not a good to the edges of the fins. conductor of heat, and a radiator in which the entire core is dipped is a relatively inefficient unit. After the core is thus completed, upper and lower water ltanks may be secured in any manner desired, as by soldering or the like, to the upper and lower plates dll. Figure 8 shows a portion of the completedradiator, and it will be noted that the generally diamond or hexagonally shaped opening formed by the marginal portions of the strips or fins 2 serve as air passageways for leading the air in between adjacent water tubes I. The tubes themselves are spaced closer together than the width of the air passageway so that the tubes have a Venturi-like effect when air is drawn through the core for the purpose of securing a lateral ow of air in addition to the ow of air directly through the core induced by the fan or whatever other means is provided for causing air to flow through the radiator.

Aswill be apparent from Figures 2 and `8, the spacing ofthe water tubes longitudinally of the fins is equal to one-half the pitch a of the n corrugations.V It will also be noted that by virtue of the auxiliarymarginal corrugationsl, the appearance of the radiator core resembles the appearance of a cellular vradiator of vthe honeycomb type, but what .is more important, the marginal portionsof the fins are strengthened by these auxiliary corrugations, and `the radiator core is materially reenforced against damage by crushing or bending of the facesor marginal edges of ,the ns.

The principles of the present invention, es-

pecially in their broader aspects, can be embodied in radiator cores of adilferent formationthan the construction described above. For example, in Figures 11M to 20 a somewhat simplerform of radiator core is shown, one which; embodies practically all of the features mentioned above, especially those having to do with the mechanical interlocking of the plurality of ns, the separat-e and individual contacts between the iins and the Water tubes, and the attachment of the ns to the several tubes.

Referring now more particularly to Figure l1 which shows one of the ns used in the modified radiator core, it will be observed that, like the construction described above, the fin is comticular consequence.

Like the corrugations described above, the central corrugations of the strip shown in Figure 11 are in the nature of truncated pyramidal protuberances disposed laterally along the strip or fin, all being disposed to one side of the general plane of the strip. Likewise, the marginal corrugations 5l and 52, like the marginal fin corrugations 8 and 9 described above, are in general similar in formation to truncated pyramidal projections, with crests 55 disposed on the saine side of the general plane of the strip as the protuberances, and viu'th valleys 56 or intermediate portions disposed on the other side of the general plane on the strip. These corrugatlons or protuberances are formed preferably by drawing or stretching the metal of the strip from which the fin is made. As described above, this is for the purpose of increasing the active area of the fins as compared with the original area of the strip before manufacture. Moreover, to reduce the localization of stresses during this drawing or stretching operation, portions of the strip between the marginal corrugatlons 5l and 52 and the central corrugations o-r protuberances are extended, as at 58.

As best indicated in Figures l1 and 12, each of the central protuberances or corrugations 5E) have oppositely sloping side walls 60 and 6l and oppositely sloping end Walls 62 and 63, and the sloping side and end walls terminate upwardly in a flattened crest section 64. The pitch of the central protuberances or corrugations 50 is equal to twice that of the marginal corrugations 5| and 52, as best shown in Figures 12 and 15 to 17.

As in the modicatlon previously described. the n shown in Figures 11 and 12 is provided with the plurality of Water tube receiving openings 61 in the central portion of the strip. The openings 61, as best shown in Figure 12, are disposed in the sloping side walls 60 and Bl on either side of the attened crest 64 of each protuberance substantially midway between crest 64 and the adjacent valley, indicated by the reference numeral 69. At each side of the central series of openings 61 are openings arranged in two series l0 and 1l, the former being formed in the end walls 63 and in the intermediate valley portions 69 of the strip, and the openings ll are formed in the opposite end walls 62 and in the portions of the valley sections 69 between the protuberances 50. The openings lll and ll are in transverse alignment and, as best shown in Figure 12, are staggered with respect to` the series of openings 61.

Each of the tube receiving openings 61, 10, and 'll are formed in the strip by piercing, rather than punching, so that flanges 'Illa and 10b are provided around the openings, as best indicated in Figures 11 and 15 to 1'7, and, where the openings lll are elongated, as in the present construction, the end flanges b are usually in the nature of pointed projections, but it is to be understood that according to the present invention the proportions or dimensions of the flanges is not of par- Sirnilarly, the openings 61 and 1I are provided with side and end flanges 61a, 61h and lla., 1lb.

As in the modification described above, all of the strips are identical so far as their corrugations or protuberances are concerned, and after the strips have been formed into iins of the type best shown in Figure 11, they are severed at one end at a valley portion 69 and at the other end at a crest portion 64. Then the strips are assembled with alternate ones reversed so that the strips occupy the relative positions shown in Figure 18 with the valley portion 69 of one strip in engagement with the crest portions 64 of the next lower strip. By virtue of this arrangement, when the ns are assembled they are mechanically interlocked together, as best indicated in Figures 18 to 20. Referring for the moment to Figure 18 it will be noted that the strips indicated are not quite in engagement, but that the end anges or points 'lllb at the Valley portions 69 of the upper fm are adapted to register with the end flanges llb at the crest of the lower fin. Figure shows the ns in completely nested relation.

The distance between the end anges mb and 'llb in the valley portion 69 of one fin is slightly in excess of the distance between the end anges 10b and 'l lb in the crest portion of the next lowest iin, as best illustrated in Figure 20, so that when the strips are assembled these end flanges on the valley portions 69 of the n embrace the corresponding flanges on the adjacent crest section 54. Also, at each side the immediate inner portions of the side ilanges 'Illa at one side interlock with the side flanges 'l la of the next iin, as best shown in Figure 20. Each set of interlocking flanges will serve to prevent any displacement of one iin with respect to the other, either longitudinally or laterally, so that all that is required to hold all of the assembled ns in position is to keep them from separating so as to retain-the flanges in interlocking relation. As best shown in Figure 19, when the anges are thus employed to secure the fins in interlccked relation, the marginal corrugations 5I and 52 are in engagement, the valley sections 56 from one n engaging the crest sections of the adjacent iin, Figure 19 also includes a sectional view which further illustrates the manner in which the anges interlock. In fact, these flanges are telescoped in much the same manner as set forth in my prior patent referred to above, particularly when the water tubes are in place.

The water tubes are indicated by the reference numeral El), and these are inserted in the tube receiving openings El, 'l0 and 1l after the fins have been assembled and interlocked together. The presence of the tubes in the openings 'lll and 1|, whose side flanges and inner end flanges are in interlocked telescoping relation as described and as illustrated in Figures 21 and 22, serve to n1aintain the interlocked relation because of the friction between the tubes and the openings and flanges with which the tubes are in engagement. The metal from which the fins is formed possesses some resiliency and since the tube receiving openings are pierced, the flanges all extend in the same direction when the ns are severed. This facilitates the insertion of all of the tubes from one direction, the flanges frictionally gripping the tube after it has been inserted to prevent its removal. Also, since the anges 15b and 'Hb are telescoped at their inner portions the tubes hold the fins in frictional contact. While, also, the inner portions of the side flanges 'la and 'lla are in telescoping relation, the resiliency of the strips is such that at their outer portions, where the ilanges 70a and 'lla are spaced apart vertically, each has individual contact with the tubes, as indicated in Figures 20, 2l, and 22.

Referring now more particularly to Figure 19, it will be observed that the pitch of the marginal corrugations is only one-half of the pitch of the central corrugations or protuberances 55, and it will also be observed that the marginal corrugations 55-56 are displaced one-quarter of their pitch out of transverse alignment with the central corrugations or protuberances 50. By virtue of this arrangement, when alternate iins are reversed end for end, with the Water tube receiving openings in alignment and with the end and side flanges thereof mechanically interlocked as explained above, the crests 55 of each fin will engage the valley portion 56 of the adjacent iins.

' Thus, when the fins are properly assembled and the tubes inserted, the marginal corrugations 5I and 52 form the pattern of the radiator.

. The marginal corrugations of Figure 19 are only one-half the pitch of the central corrugations and they need not have the intermediate crimps described above in connection with the previous modification, since the face of the radiator core having these relatively ne pitch marginal corrug-ations offers sumcient resistance to crushing and bending. Of course, the marginal sections 5I and 52 could, if desired'be provided With such intermediate crimps similar to those indicated at i8 in the previously described niodiiication.v Also, the pitch of the marginal corrugations 5I and 52 could be doubled, particularly when provided with such crimps, inwhich case they need not be displaced out of transverseV alignment with the central corrugations, but could be, as described in the previous modification, in alignment therewith.

.Fins are arranged to provide for air passageways between the tubes, and to this end the intermediate crimps 58 referred to `above serve to somewhat enlarge these air passageways while, Y at the same time, the tubes act as Venturi-like restrictions to provide forvariations in the veloc- V ity of air through the radiator in order to promote lateral circulation.

Both of the modiiications described above are assembled in practically the same manner. As mentioned above, the individual fins as they come from the fin forming machine are -cutat a valley portion at one end and at a crest portion at the other end, and then the group of iins are assembled with -alternate ones reversed. 'I hat is, the first fin will be laid with the crest-severed and at the left, for example, and then the next iin will be laid oppositely, that is, with its creste severed end at the right. The next iin will then be laid with its crest-severed'end to the left, and the next will be laid with its crest-severed end to the right and so on. As the core is thus built up to the required size, each iin as it is laid is mechanically interlocked` With the next lower iin by virtue of the interengaging flanges 10a, 10b, "Ha, and 1lb. The core end plates 95 are assembled with the fins, that is, the bottom end plate is laid rst, then the iins are assembled as indicated above, and nally when the core has been completed, the upper or top plate is laid. After the radiator core has been formed to the desired size, the assembled ns areplaced in a jig and compressed slightly to the proper size. This compression is relatively slight and is easily accommodated by the resiliency of the fins., While it is held in a jig, the water tubes are inserted from the upper end, that is, from vthe upper end of the core where the flanges are extended downwardly. The curvature of the metal immediately surrounding the tube receiving openings serve to guide the tubes and facilitate their insertion in the aligned or registering tube receiving openings. `This can lbe done relatively 4the first modification and can be used in assemv invention are of the double-lockseam type, but

it is to be understood that the seamless tubes may be used if desired. f Y

Preferably, according to the principles of the present invention, the tubes before insertion in the fins have been tlnned, and then after the core has been assembled and the tubes inserted, the core is baked or heated to a point above the melting point of tin for a short period of time, so that when the core is removed and cools, the tin sets and secures each n to all of the tubes, that is, each of the side and end anges are, in eiiect, permanently fastened to the tube in intimate and firm contact Without the use of solder or without dipping the core itself.

This is a very important advantage of the pres. ent invention. First, solder is a relatively heavy substance, and, second, its heat conductivity is relatively low so that a radiator dipped in solder is heavy and ineicient thermally. I avoid these disadvantages by securing each iin t each of the tubes in the above manner, and in both modications each iin is `secured to each tube in spaced relation with respect to the other ns. This is literally true in the case of thefirst modi- `fcation and, for all practical purposes is true for the second modification, the only difference being that, as indicated in Figures 20, 21, and 22, portions of the inner sections of the side flanges and end anges of the openings 'm and 1I are mechanically telescoped a short distance. However, as best shown in Figures 2O and 22, the major portion of the side lianges 70a, and 'l I a are in .individual contact with the associated water tubes.

After the radiator core has thus been baked and cooled to set the tin, and thus secure the ns to the tubes, the front and back faces of the radiator core are dipped in a thin bath of solder justsuiiicient to secure the contacting portion of the marginal corrugations together 5i and 52. Also, the top and bottom plates of the radiator core are dipped in a bath of solder to rigidly fasten the plates to the ends of the tubes.

While I have shown and described above the rpreferred structure in which the principles of of the strip, tube receiving openings formed in the sloping sides of said protuberances, and other tube receiving openings in said strip spaced from said iirst tube receiving openings.

A 2. A plurality ofi'ins having central corrugatlons of a given pitch and height, marginal co1'- rugations having the same height as said central corrugations and a pitch equal to one half of the pitch of said central corrugations, and tube receiving openings formed in the central corrugations on opposite sides thereof in symmetrical sets, the marginal corrugations being disposed out of registry with said central corrugations a distance equal to one quarter of the pitch of the latter, the disposition of said marginal corrugations being such that when one of said fins is reversed endrfor end with respect to the other and the tube receiving openings are aligned, the high and low points, respectively, of each of said sets of corrugations are in engagement, said tube receiving openings being arranged to be in registry with the tube receiving openings in the other ns bothv before and after reversal of alternate fins.

3. A radiator fin comprising a strip of metal having a central series of protuberances extending in the same direction from the plane of the strip, there being pairs of flanged tube receiving openings in the crests of said protuberances and in the spaces between the protuberances the distance between the adjacent ends of the openings in the spaces between the protuberances being slightly different than the distance between the adjacent ends of the openings in the crests of said protuberances, whereby the portions of said flanges at said ends interlock in telescoping relation whenever the strips are assembled with said openings in alignment and with the crests of the protuberances of one strip registering with the intermediate spaces between the protuberances of the adjacent strip.

4. A plurality of identical radiator fins, each comprising a series of centrally disposed corrugations having tube receiving openings spaced on either side of the crests thereof, a series of marginal corrugations, said central corrugations being disposed all at one side of the original plane of the strip and the marginal corrugations being disposed first to one side and then to the other side of said plane, the pitch of the marginal corrugations and their disposition relative to said tube receiving openings being `such that, when the fins are assembled with alternate ones reversed end to end, corresponding tube receiving openings are in alignment and the crests of the central and marginal corrugations of each strip meet, respectively, the intermediate portions between the crests of the central and marginal corrugations of the adjacent strip.

5. A plurality of identical radiator fins, each comprising a strip of metal having a series of spaced truncated pyramidal protuberances formed in the central portion of the strip, corrugated marginal portions at the edges of the strip, a set of flanged openings at the sides of the crests of said protuberances, and a second set of flanged openings disposed in the strip between said protuberances, portions of the anges of one set of openings cooperating with the other set of openings, when the strips are assembled with alternate strips reversed end for end, to interlock all of said strips and hold them against relative displacement, the corrugations of said marginal portions being spaced longitudinally of the fin with respect to the central protuberances and said flanged openings thereof, so that when alternate strips are reversed end for end and said hanged openings interlocked the marginal portions form a connected protecting pattern.

6. A radiator core comprising a plurality of fins and tubes, said iins having portions with flanged openings receiving said tubes and arranged at an angle to one another, so that at one point the anges of adjacent openings overlap, whereby the ns are mechanically interlocked together and at other points the flanges are spaced apart and have separate contact with the tubes.

'7. A radiator core of the fin and tube type comprising a plurality of ns having sets of tube receiving openings with portions mechanically interlocked together, the other portions of the fins being spaced apart and provided with other sets of tube receiving openings therein, tubes disposed in said interlocked tube receiving openings, and other tubes disposed in said spaced openings.

8. A radiator core comprising a plurality of corrugated fins having central portions mechanically interlocked together and marginal portions also corrugated with parts of the marginal corrugations of one strip in engagement with and secured to parts of the marginal portions of the adjacent strips to form the external pattern 0f the core there being tube receiving openings on opposite sides of the mechanically interlocked portions in the central section of the fins, and Water tubes disposed in said openings, said ns being out of contact with one another between said marginal corrugations and the central 1nterlocked portions of the fins.

9. A radiator core of the 1in and tube type comprising a plurality of fins formed of strip material, each fin having portions offset in opposite directions from the general'plane of the strip and said fins being assembled with certain portions of adjacent strips in direct contact and other portions of said strips spaced apart a distance equal to twice the distance between the general planes of said strips, means at the portions of said strips in direct contact for mechanically interlocking adjacent flns together, aligned tube receiving openings in the fins separate from said interlocking means and intermediate the portions of the adjacent strips in direct contact and the portions thereof spaced farthest apart, and tubes disposed in said openings and contacting said fins.

10. A radiator core of the fin and tube type comprising a plurality of water tubes and fins having central and marginal corrugations of equal pitch, each of the central corrugations having a plurality of openings to receive said tubes and said fins being assembled with their corrugations in contact to form cellular passage- Ways for the flow of air therethrough and around the tubes, the corrugations of the marginal portions being crimped between the crest and in vert portions thereof in a direction transversely of the core so as to strengthen the face of the core against damage.

11. A radiator core of the fin and tube type comprising a plurality of water tubes and corrugated fins having openings to receive said tubes, the central corrugations of the n having a pitch twice that of the corrugations in the marginal sections of the ns, said fins being assembled with their corrugations in contact to form cellular passageways for the flow of air through the tubes, and the tubes being spaced in the core a distance substantially equal to the pitch of said marginal corrugations.

12. A radiator iin comprising a strip of metal having a series of spaced truncated pyramidal protuberances formed in the central portion of the strip, a plurality of rows of tube receiving i aovspss y n openings formedin the fin, each of the openings of one row lying Wholly in the sloping sides of said protuberances between the crest and bottom of each and the tube receiving openings of at least one other row extending into the sloping end portions of said truncated pyramidal prof tuberances.

13. A radiator fm comprising a strip of metal having a central series of protuberances extend# 10 ing in the same direction from the plane of the strip, there being flanged tube receiving openings lying wholly in the sides of the crests of said protuberances, and aligning flanges spaced longitudinally of the strip from said tube receiving 15 openings and disposed in the crests of the protuberances.

14. A radiator ln comprising a strip of metal having a central series of protuberances of generally pyramidal formatiom there being tube 20 receiving openings in the sloping sides and ends of each of the protuberances, and a series of marginal corrugations formed in opposite edges 'of the strip and displaced from points in transverse alignment with said protuberances a distance substantially equal to one-fourth the pitch of the marginal corrugations. 1

15. A radiator core comprising a plurality of identical radiator ns, each consisting oa strip having a series of spaced truncated pyramidal protubeiances formed in the central portion thereof and separate marginal corrugations disposed longitudinally of the strip out of transverse alignment with respect to the central protuberances, there being tube receiving openings in the sloping sides and ends of the protuberances and in the spaces between the latter, the marginal corrugations being disposed longitudinally of the strip out of transverse alignment with the tube openings a distance equal to a fraction of their pitch, whereby when alternate fins are reversed end for end and the tube openings in adjacent strips aligned so that the inner ends of the openings in the intermediate portions of the strips engage the inner ends of the Opening in the crests, the marginal corrugations of adjacent strips are brought together to form a connected protecting pattern.

FRED M. OPITZ. 

